Privacy
Last updated 14 October 2026
Quit21 keeps what you write on your phone. This page describes the app, the ads in it, the purchase that removes them, and this website separately, because they work differently.
The app
Everything you enter in Quit21 stays on your phone, in a database that only the app can read. There is no account, no sign-up and no server of ours. Your quit date, what you smoked, what it cost, the reasons you wrote, every craving and slip you log and the notes you add to your days are stored on the phone. None of it is ever sent to the developer, and none of it is passed to the advertising code described below.
The phone itself may keep a backup copy of the app's data, the same way it does for other apps. On Android this is Android's backup in your own Google account. On iPhone it is part of the phone's iCloud backup, or of a backup to your computer, if you use one. These backups are the phone's, not ours. They are tied to your own account, only your devices can restore them, and the developer has no access to them. They are what let your history come back if you move to a new phone. You can turn them off in your phone's backup settings.
Nobody, including the developer, can read your data, recover it or delete it on your behalf. You can delete all of it yourself in the app's Settings. Uninstalling the app also removes it from the phone. A backup copy in your Google account or in iCloud is replaced at the next backup, and you can remove it in that account's backup settings.
The app contains no analytics of its own.
Notifications are scheduled by your phone. They are not sent from a server and do not require an internet connection.
The ads
The app shows a banner at the foot of the home screen, the first screen of SOS and the diary. It never appears on a day's page, during the breathing exercise, or while you log a craving or close a day. The banners are served by Google AdMob, provided in the European Economic Area by Google Ireland Limited.
To request and show an ad, Google's advertising code in the app collects information about the device. This includes the advertising ID, the device model and operating system, the language, an approximate location derived from the IP address, and whether an ad was shown or tapped. Google uses it to deliver and measure ads, to prevent fraud and, if you agree, to personalise the ads you see. Google is responsible for this data under its own privacy policy, and explains here how it uses information from apps that show its ads.
Ad requests carry nothing from your data in Quit21. Your quit date, your diary, your slips and your reasons are never sent to Google, and ads are not targeted using them.
In the European Economic Area, the United Kingdom and Switzerland, the app asks for your choice with Google's consent form before any ad is requested. You can change that choice at any time under Ad privacy choices in the app's Settings.
On iPhone, the app also shows Apple's own App Tracking Transparency prompt, which asks whether the advertising identifier may be used to track you across other companies' apps and websites. If you choose Ask App Not to Track, the identifier is not available to the app or to Google's advertising code, and ads are not personalised with it. You can change this at any time in the iPhone's Settings, under Privacy & Security, Tracking.
On Android, you can reset or delete your advertising ID in your phone's settings.
Removing the ads
Remove ads is a one-time purchase made through Google Play, and is currently available on Android only. Payment is handled entirely by Google, and the developer never sees your card or payment details. Google provides the developer with the order record it keeps for every Play purchase, such as the order number, the date, the price and the country.
Once you have bought it, the app does not request ads anywhere and does not show the consent form. On each start it asks Google Play whether the purchase is still yours and keeps the answer on the phone, so the purchase comes back on a new phone signed in to the same Google account.
This website
quit21.app is a set of static files. It sets no cookies, runs no analytics and loads nothing from third parties. The fonts are served from this domain rather than from a font provider.
The site is hosted by Render (Render Services, Inc.), which keeps standard server logs, including the IP address of each request, for security and operational purposes.
If you write to the address on this site, the message is held in that mailbox so it can be replied to. It is not used for anything else and there is no mailing list.
Children
Quit21 is intended for adults who smoke or vape and is not directed at children.
Your rights
Under the GDPR you have rights of access, rectification, erasure, restriction, portability and objection in respect of personal data held about you. In practice, what you enter in the app is on your phone, where only you can reach it, and the developer holds no data about your use of the app. Data collected for the ad is held by Google, and the ways to exercise your rights over it are set out in Google's privacy policy. For anything relating to purchases or email correspondence, write to the address below.
Changes
If this policy changes, the date at the top of the page changes with it.